Relationship between subsurface sedimentology and occurrence of vegetation communities of northern Minnesota boreal peatlands
- Syracuse Univ., NY (United States). Dept. of Geology
- Univ. of Minnesota, Minneapolis, MN (United States)
A recent hydrologic and pore-water chemistry study of the 7,500 km[sup 2] Lake Agassiz Peatlands in northern Minnesota suggest that local groundwater flow through the peat in the Lake Agassiz Peatland is superimposed on a regional flow system. Discharge of the regional flow system into the peasants through the underlying lacustrine sediments controls the occurrence of vegetation communities. These peatlands have distinct vegetation communities; bogs and fens. Bogs have 0.5 to 3 meters relief above adjacent fens are dominated by Picea mariana, Carex oligosperma, and ericaceous shrubs with a continuous mat of Sphagnum moss. Fens are dominated by sedges, such as Carex lasiocarpa and Rhynchospora alba and various Amblystigeaceae mosses. Bogs and fens are hydrologically distinct. It is commonly thought that bogs are isolated from groundwater, receiving most of the water from precipitation, with fens having lateral groundwater flow. The findings indicate that, contrary to common belief, bogs in Lake Agassiz are located over areas of regional groundwater discharge with a shallow local recharging system. However, during droughts the hydrology of bogs change as the regional flow system begins to dominate while the shallow recharging system diminishes. A grain size distribution study of the lacustrine sediments underlying the peat indicate that sediments under bogs are generally coarser than sediments under adjacent fens. Consequently sediments under the bogs have higher hydraulic conductivity than the adjacent fens. The implication of this study is that placement of bogs may be controlled by regional groundwater discharge through areas of high hydraulic conductivity.
- OSTI ID:
- 5578798
- Report Number(s):
- CONF-921058-; CODEN: GAAPBC
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Vol. 24:7; Conference: 1992 annual meeting of the Geological Society of America (GSA), Cincinnati, OH (United States), 26-29 Oct 1992; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
01 COAL, LIGNITE, AND PEAT
MINNESOTA
WETLANDS
HYDROLOGY
DRAINAGE
FLUID FLOW
GROUND WATER
HYDRAULIC CONDUCTIVITY
PEAT
PLANTS
RECHARGE
SEDIMENTS
AQUATIC ECOSYSTEMS
DEVELOPED COUNTRIES
ECOSYSTEMS
ENERGY SOURCES
FOSSIL FUELS
FUELS
HYDROGEN COMPOUNDS
MATTER
NORTH AMERICA
ORGANIC MATTER
OXYGEN COMPOUNDS
USA
WATER
580000* - Geosciences
011000 - Coal
Lignite
& Peat- Reserves
Geology
& Exploration